Filler composition



Patented Nov. 17, 1942 2.302.286 "FILLER comosmon Ernest G. Almy,Tamaqua, -Pa., assignor to Atlas Powder Company, Wilmington, Del., acorporation of Delaware No Drawing. Application April 25, 1940,

Serial No. 331,532

Claims.

The present invention relates to improvements in a filler composition.

In the processes of finishing porous'mater'ials such as wood, it issometimes necessary because of the fibrous character of the surface tolay a foundation for a finishing lacquer or varnish coat.

. This foundation serves to fill the pores of the wood which open uponthe surface and thereby produces a smooth surface for the reception ofthe finishing coat. Without this foundation the finishing coat wouldtend to follow the contour of the surface of the wood resulting in anuneven coating falling into the depressions in the surface of the wood.A further difficulty in coating unfilled wood .is that an excessiveamount of coating material is required. It is known that i an ultimatelysatisfactory coating can be precannot be applied readily and furthermorewill not remain in th pores of the wood during'subsequent handlingbefore the coating is applied. It is, therefore, recognized as.necessary to provide some sort of binding agent along with the inertfilling material. The most satisfactory binding agent prior to thepresent invention has'been a drying oil. A filler of the oil type thencomprises inert filling material, drying oil, hydrocarbon solvents, andusually a drying accelerator. Saponifying agents are sometimes used toreact with part of the oil and thus increase the speed of drying. Such afiller can be applied, for instance, by brushing or spraying, and thenremains open or workable for a period of some time depending on the rateof drying of the oil. In furniture finishing, for example, a fillingoperation may consist in having one manapply the filling composition bymeans of a, brush or the like and pass the work to a second man whoproceeds to pad the filler into the wood. This padding is accomplishedby hand rubbing with a coarse cloth, tow or the like. With a handful ofcloth or tow al-' ready soaked with partly dried filler,'.the filler isrubbed across the grain starting at the point where the compositionwasfirst applied by the first workman. The operation is continued usinga fresh handful of cloth or tow with a circular rubbing action all overthe surface of the wood.

' In some cases, another rubbing with the grain is For the purpose ofaccomplishing employed to remove most of the remaining excess filler. Bymeans of this padding the filler composition is forced into the pores ofthe wood and any excess is sheared oif at the surface. The

fillin operation may then be completed by a ragging off step whichconsists in going over the surface with a rag to remove fragments of towor filler and to wipe any comers or carvings which would be missed bythe padding. The ease and emciency of the filling operation dependlargely upon the physical properties of the filler. The filler mustremain workablefor a sufficient period of time to enable the completeworking of the article. In the case of large pieces of furniture, forinstance, this working period occupies a considerable period. Incommercial production the time between application of filler and thefirst aftercoating is variable and the quality of the resulting finishis subject to correspondingly undesirable variation unless the fillerremains work-. able throughout a substantial period. The action of thematerial informing a pad on the rubbing cloth ortow is also important insecuring uniform filling since once a'good pad is formed, furtherrubbing gives a substantially uniform filling action on the'wholesurface being padded. The

' filler should also cut or rub off smoothly at the that it is notstable! in contact with lacquers or varnishes. Pyroxylin lacquers areincompatible with the oil and the lacquer and filler mutually attack oneanother resulting in a failure of the coating. Any oil soluble stainused in the filler tends to bleed into whatever coat is appliedthereove'r.

A still further disadvantage with an oil filler is that it is necessary.if astaining operation is to be combined with the filler, to use oilsoluble stains. The oil soluble stains are generally unsatisfactory andfugitive and the staining operathrough fermentation, molding, etc.

tion is not-generally satisfactory when done in this manner.

Instead of an oil filler, it has been proposed from time to time to usea water filler in which some water soluble or water dispersible bindingagent is employed. The advantages of such fillers are numerous. Nocheaper or more readily available solvent is known. The materialsgenerally require only elimination of solvent in order to set.

The highly superior water soluble wood stains can be used with them.However, water soluble or water dispersible fillers are not widelyemploye at the present time. 1

Among the commonly proposed binders of this class might be mentionedanimal and vegetable glues, starches, gums, sugars, molasses, silicicacid, emulsions of waxes and "resins, and mixtures of these materialswith each other and with a wide variety of other substances. Oneobjection to most of these materials is that.they are organic in natureand subject to decomposition Another and very serious objection is thatthey require such high percentages of water for practicable applicationas to weaken their binding power to a dangerous degree. Coincidentalwith this high water percentage requirement is the fact that applicationof fillers containing such large amounts of water produces excessivegrain raismg.

Proposals tosubstitute various other materials as binders in waterfillers have not been success ful from a commercial viewpoint becausethe fillers proposed, among other things, were more expensivethan oilfillers, more difiicult to use, were not stable in storage, or requiredsome particular treatment to prepare for use or-to set them up afteruse.

It is an object of the present invention to provide an improved watersoluble filler.

Another object of the invention is to provide a. water solubl filleremploying a novel water soluble resinous binder.

A further object of the invention is to provide an oil-free filler whichsets by elimination of the solvent, permits the use of water solublewood stains, and does not raise wood grain excessively.

A still further object is to provide a water soluble filler in which isincorporated a water solubl stain. J

The above and other objects will become apparent from the followingdescription and examples of the preferred form of my invention which isnot, however, limited thereto but is limited only by the scope of'theclaims appended hereto.

I have found that a greatly improved water soluble filler can beprepared by the use of a resinous binding agent comprising a boric acidresin to'neutralize the resin by the addition of an alkali hydroxide,preferably sodium or potassium hydroxide. Y

Instead of using a pure hexitol for preparing the resin a moreeconomical commercial mixture can be employed. For example, in the caseof sorbitol there is available a commercial syrup produced by theelectrolytic reduction of glucose and which contains a major portion ofsorbitol and also considerable quantities of non-hexitol polyhydroxybodies. This material has been found to make resins with boric acidwhich are eminently suitable for the purpose of the present invention.

The filling agent used in the filler of the present invention may be anyof the well-known inerts used with the fillers of the prior art. Asexamples of such fillers may be cited the various forms of silica (suchas quartz or silex) gypsum,

slate-flour, diatomaceous. earths, various pi ments, and many otherswhich will be apparent to those skilled in this art. Of particular valuefor general application is a transparent and finely divided inert suchas silex. The diatomaceous earths are not generally suitable as the onlyfiller because they are too light and fluify. However, the bulking powerof this filler is very useful when added to other harder inerts.Diatomaceous earths also assist in rubbing ofi the excess filler,keeping the filler workable longer, and imparting the property ofrolling up when it is being rubbed off.

The preferred form of my filler also contains a surface active agent forthe purpose of lowering surface tension. Lowering the surface tensionincreases the amount of surface spreading of the material and at thesame time reduces the penetration of water into the wood by lowerin:capillary force which depends upon surface tension. A large number ofsurface active agents is known at the present time and among them may bementioned sodium oleate, soaps. particularLv soft soaps (not necessarilypotassium soaps). partial fatty acid esters of inner ethers derivablefrom hexitols, for example, mannitan monolaurate or sorbide monolaurate,these last two being particularly valuable in their commercial form suchas those prepared by using mixed coconut oilfatty acids instead of purelauric acid. The surface active agents mentioned are in no way exclusivebut any of the usual surface active agents which do not adversely affectthe resin or the aftercoating can be used.

In certain cases a filler containing water as the only solvent is foundto dry too rapi y. that is, it does not remain open or workable for asuiflcient period to enable the completion of the rubbing operation. Insuch a case a water soluof a polyhydric alcohol, which resin is watersoluble and retains its resinous properties upon drying out of watersolution. Examples of the resins which I can use are the boric acidresins of the hexitols, glycerol, or ethylene glycol, amon which theneutral resins of sorbitol and mannitol are preferred.

, The hexitol borates for use in the present inysis than the acidicresins. I, therefore, prefer his solvent can be advantageously includedin place of part of the water. Suitable solvents for this are glycol andits water-soluble derivatives such as the cellosolves and the carbitols.These materials are solvents for the resins and are water miscible buthave slower rates of evaporation than water, and so keep the filler openfor a longer period. A further advantage to the use of these solvents isthat they cause lessgrain raising than water. This is particularlyimportant under circumstances in which the filler is used at greatdilutions. If water alone were used it is possible in some cases thatundesirable grain raising would result. This effect can be prevented bysubstituting a suitable portion of the non-aqueous solvents mentionedfor part of the wa er.

It is frequently desired to include a stain with a. filler and in suchcases there are available for use in my filler a widevariety of watersoluble stains. For example, Nigroslne 12525, Buffalo Black NBR,Croceine Scarlet M00, Wool Orange A, or Fast Wool Yellow 3GL can beused. These colors are intended merely to be suggestive to those skilledin the art and it is to be understood that this list is not by any meanscomplete.

While the invention is capable of great variation as to proportions, theselection of fillers,

stains, surface active agents and the like, the following examples willindicate to, those skilled in this art some of the operativeembodiments.

Example 1- A neutral sorbitol-boric acid resin useful in the presentinvention can be made as follows:

182 g. (1 mol) sorbitol and 62 g. (1 mol) boric acid dissolved in 180 g.of water were heated at 1l0-115 C. until the water of solution and 2mols of water of condensation had been volatilized. The'meltwas thencooled to a temperature below 100 C. and a 50% aqueous solution of NaOHadded until a pH of 7.0 was obtained. This neutralization requiredexactly 0.8 mol NaOH. Thereupon the neutralized mix was heated above 100C. for sufficient time to 'evapov A filler according to the inventioncan be prepared with the following composition, parts being by weight:

Silex 60.

Sodium sorbitol borate (product of Ex. 1) 10 Water 5 Sodium oleate 1 Thesodium oleate is-suspended in the mixed borate and water. a The silexis. added and the tivey quick-drying which makes them unsuitable for useon large pieces of wood in which the application and padding time exceedthe drying time of the filler. The working life of the filler may beprolonged by the incorporation of ethylene glycol to slow-the drying. Asuitable composition can have the following proportions, parts being byweight:

Silex 48 Burnt umber 12- Sodium sorbitol borate 10 Water 2 Ethyleneglyml 4 Sodium oleate l The composition is prepared similarly to that ofExample 2, the ethylene glycol being incorporated in the liquid phase ofthe mixture.

Example 5 In place of sodium oleate which is the surface active agent ofExamples 2 to 4 other agents can be used. A commercial surface activeagent comprising principally a partial higher fatty acid ester of aninner ether derivable from a hexitol, for example, sorbide monolaurateof commercial grade, can be used. The physical character of the fillercan also be modified by replacing part of -the flinty silex by a bulkydiatomaceous earth such as kieselguhr. A formula embodying these twomodifications can have the following composition, parts being by weight:

Silex 32 Kieselguhr l6 Burnt umber 12 Sodium sorbitol borate 12 Water i2.4 Ethylene glycol 4 Monolaurate of sorbide (commercial) 0.4

Example 6- A glyceryl borate resin can be prepared as follows:

Heat 184 g. (2 mols) glycerol and 124 g. (2 mols) boric' acidslowly,'holding it at approximately 10 degree intervals until rapidboiling whole mixed thoroughly in a suitable mill. The

resulting composition is a powder which may be cut with water to anydesired consistency for application; Color may be controlled by theaddition of a water soluble stain.

E'rcample 3 A filler which is colored by means of a mineral pigment inplace of a stain can have the following composition, parts being byweight: 4

Silex 48 Burnt umber 12 Sodium sorbitol borate 10 Water 5' Sodium oleatev 1 This composition is suitable for filling walnut.

The mixture is prepared as in Example 2, Walnut filled with this mixturemay be sanded lightly and coated with lacquer or varnish without the useof further stain or sealer.

Example 4" The compositions of Examples 2 and 3 contain water alone assolvent and are, therefore, relaceases at each temperature. Samplestaken at different temperatures were very soft on cooling until thereacting mass reached 135 C. when the samples began to show signs ofresin formation by thickening on cooling. At 145 C. the mass is becomingresinous. Cool to C. and hentralize by the addition of 25 ml. of anaqueous NaOH solution of 500 g. per liter concentration. Reheat to C.until rapid boiling ceases. The product on cooling is a fairly hardglassy resin.

In place of glycerol the same reaction can be performed by substitutingethylene glycol in the same molar ratio and heating untilthe massbecomes resinous. The product of such a reaction is a glycol borateresin.

Ewample 7 In place of a hexitol borate a satisfactory filler can be madewith a glyceryl borate resin such as that of Example .6. A suitableformula can have the following proportions. parts being by weight:

Silex i 52-.

Kieselguhr 8% Glyceryl borate 12 Sodium oleate Water enough to form acreamy paste.

This binder was then applied to a sanded oak panel. The filling wasessentially satisfactory.

Example 8 I A further modification in the resinous part of the filler isto substitute glycol borate such as that of Example 6 for the otherresins. Such a composition can contain the following. parts being byweight:

Silex 52 Glycol borate 13 Sodium oleate 1 Water enough to form a creamypaste. Kieselguhr 8 A panel was filled successfully with thiscomposition although it does not dry to as hard a film as the fillersprepared with hexitol resins.

The fillers of the present invention can be substituted directly for theoil fillers customary in this art. The same mode of application andpadding can be used. Similar inert fillers are available. Asdistinguished, however, from the oil fillers, the fillers of the presentinvention can be coated at once when the water or other solvent hasevaporated. There is no chemical change involved in the setting of thisfiller, but it is a simple drying out. The aqueous solvent is partlyabsorbed into the wood and partly evaporates. The small amount of waterabsorbed into the wood does not produce any undesirable efiects inordinary usage. Where a large quantity of solvent must be used and anall water solvent might produce grain raising, part or all of the wateris replaced by glycol ora derivative thereof. The filler does not reactadversely to a lacquer or varnish coating and there is no hydrocarbonsolvent to eliminate. In the case of the ethylene glycol and itsderivatives, the vapors are unobout of the grain better than similarpanels filled bitol borate filler of the type described herein,

retained its original finish under the same conditions.

Another advantage possessed by the fillers of the present invention isthat wood filled with them can be sanded if desired. Such sanding can beperformed as soon as the filler dries. In many finishing operations,particularly in fine finishing work, this is a real advantage, whereasit is recognized that an oil filler does not sand well due to rapidclogging of sand paper.

The invention is not to be taken aslimited to the examples since otherpolyhydric alcohol boric acid resins which are watersoluble and retaintheir resinous properties upon d ying out of water solution can be used.Similarly,'the other ingredients of the filler and the proportionsthereof are subject to variation as already described. The consistencyof the filler can be varied by controlling the amount of water (andwater soluble organic solvent) used. For some P poses a relatively thickpaste-like consistency will be preferred but for other purposes abrushable or even a sprayable consistency may be desired. In any casethe consistency wanted can be obtained by using more or less liquid inthe composition as will be apparent to those skilled in the art.

resinous character on drying out or water solution and being a binderfor said filling material.

2. A filler comprising inert filling material and an aqueous solution ofa water-soluble resin of boric acid and a polyhydric alcohol selectedfrom the group consisting of hexitols, glycerol and ethylene glycol,said resin retaining its resinous prop erties upon drying out of watersolution and being a binder for said filling material.

3. A filler comprising inert filling material and an aqueous solution ofa water-soluble boric acidhexitol resin, said resin retaining itsresinous properties upon drying out of water solution and being a binderfor said filling material.

4. A filler comprising inert filling material and an aqueous solution ofa water-soluble boric acidmannitol resin, said resin retaining itsresinous properties upon drying out of water solution and being a binderfor said filling material.

5. A filler comprising inert filling material and an aqueous solution oia water-soluble alkali metal neutralized boric acid-mannitol resin, saidresin retaining its resinous properties upon drying out of watersolution and being a binder for said filling material.

6. A filler comprising inert filling matrial, an aqueous solution of awater-soluble alkali metal neutralized boric acid-mannitol resin, saidresin retaining its resinous properties upon drying out of watersolution and being a binder for said filling material, and a surfaceactive agent.

7. A filler comprising inert filling material and an aqueous solution ofa water-soluble boric acidsorbitol resin, said resin retaining itsresinous properties upon dryingout of water solution and being a binderfor said filling material.

8. A filler comprising inert filling material and an aqueous solution ofa water-soluble alkali metal neutralized boric acid-sorbitol resin, saidresin retaining its resinous properties upon drying out of watersolution and being a binder for said filling material.

9. A filler comprising inert filling material and an aqueous solution ofsodium sorbitol monoborate, said monoborate being a binder for saidfilling material.

10. A filler comprising inert filling material, an aqueous solution ofsodium sorbitol monoborate, said monoborate being a binder forsaidi-filling material, and a surface active agent.

11. A filler comprising inert filling material, an aqueous solution of awater-soluble boric acidpolyhydric alcohol resin, said resin retainingits resinous properties upon drying out of water solution and being abinder for said filling material, and anauxiliary solvent for said resinselected from the group consisting of ethylene glycol and water solublederivatives of ethylene glycol.

12. A filler comprising inert filling material, an aqueous solution of abinder consisting of a resin of boric acid and a polyhydric alcoholselected from the group consisting of hexitols, glycerol,

and ethylene glycol, said resin being water soluble and retaining itsresinous properties upon drying out of-water solution, and an auxiliarysolvent for said resin selected from the group consisting of ethyleneglycol and water soluble derivatives of ethylene glycol.

13. A filler comprising inert filling material, an aqueous solution of abinder consisting of a resin of boric acid and a polyhydric alcoholselected consisting of ethylene glycol and water soluble derivatives 01'ethylene glycol, and a surface active agent.

14. A filler comprising inert filling material and an aqueous solutionof a boric-acid resin of a polyhydric alcohol with not more than 6hydroxyl groups, said resin being water soluble and retaining itsresinous character on drying out of water solution and acting as abinder for said filling material.

15. A filler comprising inert filling material and an aqueous solutionoi. a boric-acid polyhydricalcohol resin, said resin being watersolubleand retaining its resinous character on drying out of watersolution and being a binder for said filling material, and a surfaceactive agent.

16. A composition for dilution with water to, produce a filler whichcomprises inert filling material and a boric acid-polyhydric alcoholresin as a binder for said filling material, said resin' being one whichwill dissolve in added water and which retains its resinous character ondrying out of water solution.

17. A composition for dilution with water to produce a filler. whichcomprises inert filling material and a boric acid-hexitol resin as abinder for said filling material, said resin being one which willdissolve in added water and which retains its resinous properties upondrying out of water solution.

18. A composition for dilution with water to produce a filler whichcomprises inert filling material and an alkali metal neutralized boricacidmannltol resin as a binder, said resin being one which will dissolvein added water and retain its resinous properties upon drying out ofwater solution.

' 19. A composition for dilution with water to produce a filler whichcomprises inert filling material and an alkali metal neutralized boricacidsorbitol resin as a binder, said resin being one which will dissolvein added water and retain its resinous properties upon drying out ofwater solution.

20. A composition tor dilution with water to produce a filler whichcomprises inert filling material and a boric acid resin of a polyhydricalcohol with not more than 6 hydroxyl groups, said resin being one whichwill dissolve in added water and retain its resinous character on dryingout of water solution and acting as a binder for said filling material.

ERNEST G. ALMY.

